From the given table, we calculate the Need matrix (extNeed=extMax−extAllocation):
Need(P0)=(8−0,4−0,3−1)=(8,4,2)
Need(P1)=(6−3,2−2,0−0)=(3,0,0)
Need(P2)=(3−2,3−1,3−1)=(1,2,2)
Currently, Available=(3,2,2).
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### Analyzing REQ1:
P0 requests (0,0,2).
Request ≤Need(P0) and Request ≤Available.
If granted tentatively:
Allocation(P0)=(0,0,3)
Need(P0)=(8,4,0)
Available=(3,2,2)−(0,0,2)=(3,2,0)
Now, test for a safe sequence:
$Need(P_0) = (8, 4, 0)
leq (3, 2, 0)$
Need(P1)=(3,0,0)≤(3,2,0)⟹P1 finishes, new Available=(3,2,0)+(3,2,0)=(6,4,0)
Now:
$Need(P_0) = (8, 4, 0)
leq (6, 4, 0)−Need(P_2) = (1, 2, 2)
leq (6, 4, 0)(sinceZhas0availablebutrequires2$)
Neither P0 nor P2 can proceed. Hence, the system enters an unsafe state.
Therefore, REQ1 cannot be permitted.
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### Analyzing REQ2:
P1 requests (2,0,0).
Request ≤Need(P1) and Request ≤Available.
If granted tentatively:
Allocation(P1)=(5,2,0)
Need(P1)=(1,0,0)
Available=(3,2,2)−(2,0,0)=(1,2,2)
Now, test for a safe sequence:
Need(P1)=(1,0,0)≤(1,2,2)⟹P1 finishes, new Available=(1,2,2)+(5,2,0)=(6,4,2)
Next, Need(P2)=(1,2,2)≤(6,4,2)⟹P2 finishes, new Available=(6,4,2)+(2,1,1)=(8,5,3)
Next, Need(P0)=(8,4,2)≤(8,5,3)⟹P0 finishes.
A safe sequence ⟨P1,P2,P0⟩ exists.
Therefore, REQ2 can be permitted.
Thus, Only REQ2 can be permitted (Option B).